Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D233/00—Heterocyclic compounds containing 1,3-diazole or hydrogenated 1,3-diazole rings, not condensed with other rings
  • C07D233/04—Heterocyclic compounds containing 1,3-diazole or hydrogenated 1,3-diazole rings, not condensed with other rings having one double bond between ring members or between a ring member and a non-ring member
  • C07D233/28—Heterocyclic compounds containing 1,3-diazole or hydrogenated 1,3-diazole rings, not condensed with other rings having one double bond between ring members or between a ring member and a non-ring member with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K51/00—Preparations containing radioactive substances for use in therapy or testing in vivo
  • A61K51/02—Preparations containing radioactive substances for use in therapy or testing in vivo characterised by the carrier, i.e. characterised by the agent or material covalently linked or complexing the radioactive nucleus
  • A61K51/04—Organic compounds
  • A61K51/0474—Organic compounds complexes or complex-forming compounds, i.e. wherein a radioactive metal (e.g. 111In3+) is complexed or chelated by, e.g. a N2S2, N3S, NS3, N4 chelating group
  • A61K51/0478—Organic compounds complexes or complex-forming compounds, i.e. wherein a radioactive metal (e.g. 111In3+) is complexed or chelated by, e.g. a N2S2, N3S, NS3, N4 chelating group complexes from non-cyclic ligands, e.g. EDTA, MAG3
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P35/00—Antineoplastic agents
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07B—GENERAL METHODS OF ORGANIC CHEMISTRY; APPARATUS THEREFOR
  • C07B59/00—Introduction of isotopes of elements into organic compounds ; Labelled organic compounds per se
  • C07B59/004—Acyclic, carbocyclic or heterocyclic compounds containing elements other than carbon, hydrogen, halogen, oxygen, nitrogen, sulfur, selenium or tellurium
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C251/00—Compounds containing nitrogen atoms doubly-bound to a carbon skeleton
  • C07C251/32—Oximes
  • C07C251/34—Oximes with oxygen atoms of oxyimino groups bound to hydrogen atoms or to carbon atoms of unsubstituted hydrocarbon radicals
  • C07C251/36—Oximes with oxygen atoms of oxyimino groups bound to hydrogen atoms or to carbon atoms of unsubstituted hydrocarbon radicals with the carbon atoms of the oxyimino groups bound to hydrogen atoms or to acyclic carbon atoms

Definitions

• US 4615876 discloses neutral technetium complexes of diaminedioxime (or bis aminooxime) ligands having 2 to
• PnAO which forms stable, relatively lipophilic technetium complexes.
• PnAO analogues and derivatives are disclosed for various radiopharmaceutical applications including brain imaging and myocardial metabolism studies (using PnAO-fatty acid conjugates) .
• the only butylene-bridged ligand complex prepared was the parent Tc-BnAO which was shown to be neutral, stable and less lipophilic than Tc-PnAO.
• Tc-BnAO was found to exhibit insignificant brain uptake (0.12% injected dose at 30 sec pi) whereas with Tc-EnAO and Tc-PnAO the figures are 0.74% and 1.3% respectively. Consequently subsequent radiopharmaceutical development focused on PnAO ligands and desmethylated PnAO analogues have been patented as technetium brain imaging agents (US 4789736 and US 4818813) .
• Troutner et al. ' (1986) disclosed the technetium complex of an EnAO analogue with expanded chelate rings, H 2 dddo. The complex was found to be less lipophilic than Tc-PnAO.
• Radiopharmaceuticals which selectively concentrate in hypoxic cells are highly desirable since they could permit the diagnosis of potentially salvageable tissue which is at risk of infarction.
• Organs of interest for imaging would include heart and brain.
• Certain tumours are also known to be hypoxic, hence a hypoxia-specific radiopharmaceutical could also be used for the diagnosis and radiotherapy of tumours. It is also believed that hypoxia-selective radiopharmaceuticals could be useful for the detection of peripheral vascular disease.
• nitro-heteroaromatic compounds including radiosensitisers such as misonidazole are known to be trapped in hypoxic cells.
• Preferred examples are 2- nitroimidazoles.
• 18F-radiolabelled and radioiodinated misonidazole analogues have been described for hypoxia imaging and include 123I-iodoazomycin arabinoside (IAZA) (6,7 and 18 F-misonidazole (8) .
• the preferred isotope for radiopharmaceutical imaging is 99mTc by virtue of both its availability and imaging characteristics.
• a radiometal e.g. 99mTc, 186Re or 188Re
• a hypoxia-localising moiety such as a nitroimidazole.
• EP 417870 claims nitroimidazole conjugates of diaminediphenol and PnAO ligands.
• a complex of a diaminediphenol-nitroimidazole conjugate is disclosed which has a hypoxic/oxic ratio of 2:8 in an in vitro cell model.
• EP 441491 A1 discloses boron-capped tris (dioxime) "BATO" technetium complexes in which the boronic acid moiety is functionalised with a nitroheteroaromatic hypoxia-localising moiety.
• hypoxia localising groups are described in detail on pages 7-10 and Claims 18-22 of the application.
• the localising groups described encompass a wide range of nitroheterocycles.
• the supporting Examples are limited to 2 particular ligand systems - PnAO and BAT, but several 2- and 4-nitroimidazole conjugates of these ligands are prepared. No examples of diaminedioxi es other than PnAO are disclosed.
• US 5100885 reveals that copper (II) complexes are known both as radiosensitizers and radioprotective drugs and that it is not possible to predict which mode of action will prevail.
• US 5100885 discloses mixed ligand Cu(II) complexes of bipyridyl or phenanthroline with bidentate oxygen ligands such as diacids or diphenols as radiosensitizers. There is no suggestion of the use of radiometals for imaging and the complexes described are completely different from those claimed here.
• This invention discloses a range of ligands which form radiometal complexes capable of localising selectively in hypoxic cells.
• the conventional approach to the design of radiometal (e.g. 99mTc) hypoxia-targeting agents is simply to prepare chelate-conjugates of known hypoxia-localising or targeting moieties such as nitroheterocycles, especially nitroimidazoles.
• a conjugated targeting molecule such as a nitroimidazole
• these radiometal complexes, particularly of 99mTc have be( shown to exhibit much higher selectivity for hypoxic cells than prior art complexes.
• this invention provides radiometal complexes for imaging or radiotherapy of hypoxic tissue.
• a radiometal complex is of a substituted or unsubstituted ligand, whereby such complex has the intrinsic property of localising in tumours or hypoxic tissue, and wherein the ligand is not substituted by any hypoxia-localising moiety.
• the ligand is preferably a diaminedioxime having the structure
• n 2 - 5
• m 0 , 1 , 2 ,
• Y is independently H or R
• R, R' are independently: H, C. , Q linear or branched hydrocarbon which may be alkyl or one or more of alkenyl; alkoxy; alkoxyalkyl; primary, secondary or tertiary amide; primary, secondary or tertiary amine,- carboxylic acid; hydroxyalkyl; aryl; heterocyclic; heteroaryl or two R groups taken together with the atom(s) to which they are attached form a carbocyclic, heterocyclic, saturated or unsaturated spiro or fused ring; or the two R groups of a CR 2 or CRR' group adjacent to a NR group may be combined to give one or more -CONR- amide groups,
• the radiometal is preferably technetium, rhenium, rhodium or cobalt.
• the radiometal is preferably technetium-99m and the complex preferably has the formula [TcOL] where L is the ligand.
• the invention provides a complex having the intrinsic property of localising in tumours or hypoxic tissue, of a radiometal with a ligand having the structure
• R is -A-R , where at least one R is -A-R , where A is a 2 linking group and R is a hypoxia localising moiety,
• Y is independently H or R, and the other R and R ' are independently: H, C, .- linear or branched hydrocarbon which may be alkyl or one or more of alkenyl; alkoxy; alkoxyalkyl; primary, secondary or tertiary amide,- primary, secondary or tertiary amine; carboxylic acid; hydroxyalkyl; aryl; heterocyclic; heteroaryl or two R groups taken together with the atom(s) to which they are attached form a carbocyclic, heterocyclic, saturated or unsaturated spiro or fused ring; or the two R groups of a CR 2 or CRR ' group adjacent to a NR group may be combined to give one or more -CONR- amide groups.
• ligands described have the intrinsic property of localising in tumours or hypoxic tissue, it is nevertheless possible to link the ligand to a hypoxia-localising moiety.
• certain of the ligands described which may optionally be linked to a hypoxia localising moiety, are claimed as new compounds per se together with their radiometal complexes.
• Hypoxia-localising moieties, and techniques for linking them to metal-chelating moieties, are described in WO 94/08949 which is incorporated herein by reference.
• the invention provides radio imaging kits comprising ligands as described, preferably with stannous reducing agent in a freeze-dried state, adapted on addition of 99mTc pertechnetate to form a complex for radio imaging.
• the invention provides a method for imaging or radiotherapy of hypoxic tissue of a patient which method comprises administering to the patient an effective amount of a complex as defined.
• hypoxic cell uptake experiments in an isolated perfused heart model indicate that much of the hypoxia selectivity of the prior art 99mTc complex of Compound 5 is, in fact, due to the Tc-PnAO complex itself. This effect is seen more dramatically for the
• Comparison of 99mTc compound VII and Compound XII shows that exchanging an ethyl group for the nitroimidazole ring has little or no effect on both the hypoxic/oxic ratio and normalised hypoxic retention.
• nitroimidazole "hypoxia-localising moiety ' has minimal effect on the targeting of the radiometal complex since the intrinsic properties of the radiometal complex are predominantly responsible for the hypoxia selectivity.
• the differences which are observed with the nitroimidazole conjugates are probably largely attributable to simple alteration of the lipophilicity/hydrophilicity balance of the complex.
• 99m Tc-PnAO compared to the 99Tc complex is presumably due to the concentration of radiometal complex used in the assay.
• the ligands of this invention can be synthesised according to Schemes 1 to 5 and Examples 1 to 17.
• Dry hydrogen chloride gas was passed into a mixture of 2-methyl-2-pentene (20g, 237mmol) and iso-amyl nitrite (55.67g, 475mmol) cooled to -20°C.
• the reaction mixture was left to stir at 0 C overnight and the precipitated material was then filtered off and washed with cold (-20°C) ethanol (3 x 5ml) .
• the product was dried in a stream of air and was used without further purification, (13g, 36%).
• 2-Nitroimidazole (2g, 17.7mmol) was added to a solution of sodium hydroxide (0.76g, 19mmol) in water (20ml). Tne solution was stirred for £& 1h. at RT, the water was removed under reduced pressure and the residue dried in vacuo for at least £& 3h.
• the N-alkylated product of first step (1.0g, 5.5mmol) was dissolved in iso-amyl nitrite (1.0ml, 7.4mmol) at RT and then cooled in an ice bath (outside temp, measured -8 C) .
• Concentrated hydrochloric acid (0.9ml, 36% HC1) was added dropwise while stirring. The reaction was stirred for c , 15 min. before storing overnight at -20 C.
• Glacial acetic acid (10ml) was added and the mixture was kept at -20°C for ££ 30-35 min.
• Methanol (10ml, cold) was added and the reaction mixture was stored at 10 -15 C for QS 3h., whence a white precipitate formed.
• the product was filtered very quickly, washed with ice-cold methanol (5ml) and then dried in vacuo. yielding the compound as a white powder.
• reaction mixture was stirred for a further 1 hour and then heated to ⁇ a. 6 ' 0°C for 30 minutes.
• the reaction mixture was allowed to cool to RT and the white solid present, (NaHC0 3 /NaCl and product) was filtered off.
• the desired product was extracted into hot methanol, filtered hot, the solvent concentrated to £& 50% volume, cooled and refiltered.
• This product was prepared by the method used for Compound II, substituting 3-(5-aminopentyl)amino-3- methyl-2-butanone oxime for 3- (4-aminobutyl)amino-3- methyl-2-butanone oxime.
• This compound was prepared by the method described in the Squibb Patent : EP 544412 A2, see Example 1, p.20 - 21. '
• the solid material was found to be 1 , 12-bis(2-Nitro-1- imidazolyl)-4, 9-diaza-3, 3,10,10-tetramethyldodecan-2, 11-dione dioxime, (165mg, 35%)
• Butan-2, 3-dione monooxime (10.11g 0.1 mol) was dissolved in benzene (125 cm ) and heated under reflux.
• Ligand (0.25mg) was dissolved in a mixture of 0.1M HCl (0.1ml) and distilled water (0.9ml) in a sealed vial.
• Zinc powder (20mg) was weighed into a glass vial. The vial was capped, oversealed and purged with nitrogen gas. Nitrogen purged
• XOD Xanthine oxidase
• PBS phosphate buffered saline
• Hypoxanthine (4.1mg) was weighed into a P6 vial. The vial was capped, oversealed and purged with nitrogen gas. To the hypoxanthine was added (1ml) of the xanthine 20 oxidase in PBS.
• Rats under light anaesthesia were injected intravenously with 0.1ml of test agent. Three rats were sacrificed (anaesthesia followed by exsanguination) at 2 , 60 and 240 minutes, post- injection. The percentage of the injected dose in the excreta and organs and tissues was determined by dissection and assay for radioactivity in an automatic gamma counter. Table 2 shows the data for the complexes studied with figures expressed as percent injected dose.
• 3 H-misonidazole and 14C-DTPA are slowly infused into the perfusate for a 20 minute period.
• a 15-minute cold buffer washout period follows, y activity in the heart is monitored using a collimated Nal probe detector positioned over the heart.
• Samples of active perfusate and hearts are assayed for y counts and, following suitable processing using standard techniques, ⁇ -counts.
• a formulated freeze dried kit has been prepared which contains a lyophilised mixure of 0.20mg of Compound I, 0.04mg of methylene diphosphonic acid, 0.02mg of stannous chloride dihydrate, 2.8mg of sodium hydrogen carbonate and 4.9mg of sodium chloride.
• a kit of this composition is reconstituted with ""TC- pertechnetate generator eluate in sterile saline (0.9% w/v) , the "'Tc-complex of Compound I is formed in >98% radiochemical purity after a reaction time of fifteen minutes at room temperature.

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• 1994
  • 1994-08-03 HU HU9600228A patent/HUT73672A/hu unknown
  • 1994-08-03 CA CA002168652A patent/CA2168652A1/en not_active Abandoned
  • 1994-08-03 EP EP94922996A patent/EP0712315A1/de not_active Ceased
  • 1994-08-03 US US08/591,519 patent/US5997843A/en not_active Expired - Lifetime
  • 1994-08-03 JP JP07506288A patent/JP3083157B2/ja not_active Expired - Fee Related
  • 1994-08-03 WO PCT/GB1994/001705 patent/WO1995004552A2/en not_active Application Discontinuation
  • 1994-08-04 IL IL11057194A patent/IL110571A0/xx unknown
• 1998
  • 1998-04-07 JP JP09439398A patent/JP3190615B2/ja not_active Expired - Fee Related

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